The use of apocalyptic language is often a form of self-elevation. It allows a politician to embrace the role of lonely truth-seeker. “Of course,” Jindal said, “the politically correct crowd — when you say things like that, they’ll call you racist.” Only the honest and brave are willing to risk such opprobrium. Political figures who perceive the hidden threat are not only Diogenes searching for truth, they are Horatius defending the bridge against subversive Muslims, climate scientists, disease-ridden children or whatever.

This rhetorical strategy is a disaster for democratic discourse. It creates a cartoon version of reality in which actual problems are obscured or misdiagnosed. It avoids the hard work of drawing careful distinctions and offering nuanced judgments. It leaves some people on constant high alert; others are exhausted by an endless series of supposedly existential threats and unable to distinguish the real ones.

Above all, extreme rhetoric shapes a certain view of ideological opponents. Climate scientists and their allies, say some on the right, are not just mistaken, they are liars. They are acting out of corrupt financial and ideological motivations. No real debate is possible with people consciously engaged in a fraud or a hoax. They can’t be engaged; they can only be defeated. This approach becomes even more dangerous when opponents are defined in ethnic or religious terms. It creates an atmosphere in which neighbors are viewed as potential subversives.